Like the others said, you do not need any immunizations to go to Spain. And you CAN drink the water!
One little story: I once got deathly ill, I mean deathly ill, when I travelled to a very small town in the Valle de Jerte in Extramadura. (We were visiting my husband's family). I'm not sure what it was, maybe the aiolli, maybe the water, but I was so ill, the cousin had to take me to the village doctor. Every 100 feet, he had to pull over for me. How embarassing!
Anyway, at the "hospital", there was a sign-in book that looked as old as the middle ages. I signed my name there, as people have been doing for eons. Got a shot in my b---, and felt better two days later.
I hated what I went through, but now am grateful for such an experience!
Still, the first few days in Spain, I am always a little cautious and so I just "ease" into the cuisine slowly and not scarf down all that chorizo and morcilla immediately.